Automated storage and retrieval systems for providing high density yet readily accessible storage of articles have long been known. Commonly-owned U.S. Pat. No. 4,690,602, for example, discloses a two-dimensional array of storage bins or locations which are extractable for accessing stored articles. To achieve such access a two-dimensionally displaceable platform is movable to selected storage locations thereof and arm-like extractor elements are extendible into the storage location past the front edge of a bin for engagement with the bin sides to withdraw the bin from the array and, similarly, to reinsert the bin into the same or a different storage location.
The prior art teaches a variety of arrangements for effecting extraction and return of an array-supported storage bin or tray. Some require highly specialized or complex structural elements and assemblies that are unnecessarily subject to breakdowns or which typically require regular realignment and/or repair. Others operatively grip or grasp or otherwise engage the bins in a fashion that is somewhat less reliable or stable or secure than desired or that does not permit the apparatus to extract bins containing unusually heavy articles.